1. Field of the Invention
This invention relates to new and useful improvements in sausage casings.
2. The Prior Art
Dry sausage, of which the various salami and cervelats are examples, is usually prepared by a process which involves drying as one of the process steps. Dry sausage is ordinarily served cold, without further cooking by the consumer. The term "dry sausage" as used herein includes within its meaning the entire range of dry and semi-dry sausage products.
The manufacture of dry sausage customarily involves mixing desired proportions of fat and lean meats, beef or pork or mixtures thereof, with selected spices, seasonings, and curing materials to form an emulsion which is initially cured at a few degrees above freezing (36.degree. to 38.degree. F.) for one or two days so that they will be preserved sufficiently to be smoked and dried.
The chill cured meat emulsion is then firmly packed into casings of suitable size and shape, and the ends of the casings are tied ready for delivery to the drying room or smokehouse, depending on the type of sausage. The stuffed dry sausage is smoked and then dried, while unsmoked dry sausage is dried only. The drying and curing time will vary with the particular type of sausage being processed and to some extent with the processing conditions. However, 30 to 60 days is usually considered a minimum time, and periods of 60 to 90 days or more are used under some circumstances.
Previously, the sausage meat emulsions were stuffed into casings formed of natural materials or animal products such as sewn beef middles and hog casings. More recently, synthetic materials have been developed out of which casings could be formed, particularly casings formed of regenerated cellulose per se or of the product known in the art as fibrous casing and which is composed of cellulosic fibers, preferably a long fiber saturating tissue, impregnated with and held together by regenerated cellulose.
Fibrous casing is made by passing a ribbon of paper around a mandrel to form a tube, applying viscose to the outside surfaces of the paper tube and in between the overlapped portion thereof which is to become a seam. The viscose impregnated tube is passed through a coagulating bath containing acid wherein regeneration of the viscose takes place. The tube is then washed and dried according to the procedures described, for example, in U.S. Pat. Nos. 1,937,225 and 2,045,349.
One of the drawbacks of such regenerated cellulose casing materials is their lack of ability to shrink with the sausage during the drying of the sausage emulsion. In the preparation of dry sausages, the sausage encounters up to a 30-40% weight loss and tends to shrink away from the synthetic casing and leave gaps between the meat and the casing in which there is a tendency for mold and/or a so-called "brown ring" to develop. The brown ring is generally comprised of a layer of grease which will rapidly turn rancid during storage of the dry sausage. This problem is ordinarily not encountered when natural casings are used since natural casings tend to expand and contract with the sausage during curing.
The problem of producing regenerated cellulose casings which adhere satisfactorily to dry sausages during preparation thereof has been at least partially solved by the application of certain proteinaceous materials such as gelatin and glutraldehyde as a protein hardening agent to the interior of such casings, as disclosed in U.S. Pat. No. 3,383,223. One drawback to the use of hardened gelatin as an adhesive coating for casing interiors is that the coating may adhere too well to the meat, with the result that when it is attempted to remove the casing from the meat mass, there is occasionally a tendency for some meat to adhere to the casing and be torn from the sausage with the casing, thereby causing surface marring of the sausage. In other instances, due to variations in the meat emulsion formulations or in the processing conditions, there can result a degree of adherence of the casing to the meat product which hinders removal of the casing from the product encased therein to a degree that a substantial amount of meat product is removed with the casing.